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Particle board
.]] Particle board, or particleboard (or chipboard in the UK, Australia and some other countries), is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded. Particleboard is a composite material. Characteristics Particleboard is cheaper, denser and more uniform than conventional wood and plywood and is substituted for them when appearance and strength are less important than cost. However, particleboard can be made more attractive by painting or the use of wood veneers that are glued onto surfaces that will be visible. Though it is denser than conventional wood, it is the lightest and weakest type of fiberboard, except for insulation board. Medium-density fibreboard and hardboard, also called high-density fiberboard, are stronger and denser than particleboard. A major disadvantage of particleboard is that it is very prone to expansion and discoloration due to moisture, particularly when it is not covered with paint or another sealer. Therefore, it is rarely used outdoors or places that have high levels of moisture, with the exception of some bathrooms, kitchens and laundries, where it is commonly used as an underlayment beneath a continuous sheet of vinyl floor coverings History and development Modern plywood, as an alternative to natural wood, was invented in the 19th century, but by the end of the 1940s there was not enough lumber around to manufacture plywood affordably. Particleboard was intended to be a replacement. The first commercial piece was produced during World War II at a factory in Bremen, Germany. It used waste material such as planer shavings, offcuts or sawdust, hammer-milled into chips, and bound together with a phenolic resin. Hammer-milling involves smashing material into smaller and smaller pieces until they pass out through a screen. Most other early particleboard manufacturers used similar processes, though often with slightly different resins. It was found that better strength, appearance and resin economy could be achieved by using more uniform, manufactured chips. Manufacturers began processing solid birch, beech, alder, pine and spruce into consistent chips and flakes. These finer layers were then placed on the outsides of the board, with the central section composed of coarser, cheaper chips. This type of board is known as three-layer particleboard. More recently, graded-density particleboard has also evolved. It contains particles that gradually become smaller as they get closer to the surface Manufacturing Particleboard is manufactured by mixing wood particles or flakes together with a resin and forming the mix into a sheet. The raw material to be used for the particles is fed into a disc chipper with between four and sixteen radially arranged blades. The particles are first dried, after which any oversized or undersized particles are screened out. Resin, in liquid form, is then sprayed through nozzles onto the particles. There are several types of resins that are commonly used. Amino, formaldehyde based resins are the best performing when considering cost and ease of use. Urea Melamine resins are used to offer water resistance with increased melamine offering enhanced resistance. Phenol formaldehyde is typically used where the panel is used in external applications due to the increased water resistance offered by phenolic resins and also the colour of the resin resulting in a darker panel. Melamine Urea phenolic formaldehyde resins exist as a compromise. To enhance the panel properties even further the use of resorcinol resins typically mixed with phenolic resins are used, but this is usually used with plywood for marine applications and a rare occasion in panel production. Panel production involves various other chemicals — including wax, dyes, wetting agents, release agents — to make the final product water resiantant, fireproof, insect proof, or to give it some other quality. Once the resin has been mixed with the particles, the liquid mixture is made into a sheet. A weighing device notes the weight of flakes, and they are distributed into position by rotating rakes. In graded-density particleboard, the flakes are spread by an air jet that throws finer particles further than coarse ones. Two such jets, reversed, allow the particles to build up from fine to coarse and back to fine. The sheets formed are then cold-compressed to reduce their thickness and make them easier to transport. Later, they are compressed again, under pressures between two and three megapascals and temperatures between 140 °C and 220 °C. This process sets and hardens the glue. All aspects of this entire process must be carefully controlled to ensure the correct size, density and consistency of the board. The boards are then cooled, trimmed and sanded. They can then be sold as raw board or surface improved through the addition of a wood veneer or laminate surface. Furniture design Particleboard has had an enormous influence on furniture design. In the early 1950s, particleboard kitchens started to come into use in furniture construction but, in many cases, it remained more expensive than solid wood. A particleboard kitchen was only available to the very wealthy. Once the technology was more developed, particleboard became cheaper. Large companies such as Freedom and Ikea base their strategies around providing well-designed furniture at a low price. In almost all cases, this means particleboard or MDF or similar. Ikea’s stated mission is to “create well-designed home furniture at prices so low as many people as possible will be able to afford them”. They do this by using the cheapest materials possible, as do most other major furniture providers. As a result, solid wood furniture has become an expensive luxury and particleboard or MDF or similar is the norm. Safety Safety concerns are two part, one being fine dust released when particleboard is machined (e.g., sawing or routing), and occupational exposure limits exist in many countries recognising the hazard of wood dusts. The other concern is with the release of formaldehyde. And the release of volatile organic compounds from particleboard. Formaldehyde is classified by the WHO as a probable human carcinogen . Comparison of solid wood to particleboard Particleboard’s selling points compared to solid timber are its low cost, its availability in large flat sheets, and its ability to be decorated with melamine based overlays. Solid wood has structural advantages over particleboard. It is stronger, particularly in extension (as required for horizontal spans), allowing it to support greater weights as shelves or other furniture; unless braced or built with thick material, particleboard shelves may visibly sag over time or snap near the fasteners. Fasteners should be designed specially for particleboard; ordinary screws and nails will not provide the correct holding power over time. Threads may strip, portions of the particleboard may "blow out" when subjected to extension stress. In part this arises from the lack of elasticity in particleboard resins as compared to the long strands and compressible voids contained in solid wood, a feature that, while preserved in the manufacture of plywood, is compromised in particleboard. The strength of particleboard, in the context of the application and cost, can offer advantages over solid wood. In cabinet carcass construction, relatively thick particleboard is used (typically ¾"), particularly in the sidewalls to support compressive loads of countertops and appliances, where its lower cost and adequate strength make it a frequent choice. Solid wood is more durable than particleboard. Damage to solid wood can be repaired by removing and replacing damaged material then refinishing using known wood treatments that can be matched. Since particleboard is typically faced with by a non-wood veneer, it may be impossible to match the original finish. In addition, damage to particleboard is typified by structural failure and exposure of sizable jagged faults. Damage to particleboard is therefore normally very difficult to repair, usually requiring replacement of the damaged particleboard elements. The reduced durability of particleboard furniture is a consequence of reduced strength in extension. This drawback contributes to damage when furniture is moved; if possible, the furniture should be disassembled to eliminate the possibility of damage in transit. Most people consider solid wood furniture to be more attractive than particleboard. Recognizing this, furniture makers often cover particleboard with real or imitation veneers, in an effort to simulate the look of solid wood. Comparison of tropical-mix wood particleboard to rubber-wood particleboard Some particleboard today is manufactured of rubber wood, mainly from Thailand and some regions of Malaysia. Tropical-mix wood accounts for a smaller percentage of the total production of particleboard from the Asian Region. Tropical-mix wood's main differences with rubber-wood particleboard is its color, strength, and density. Tropical-mix wood particleboard, made from timber residues and wood waste, gives it a competitive edge over rubber-wood particleboard with its high bending strength. Tropical-mix wood furniture reduces wear and tear of a furniture, including common issues such as dented edges after collision, however rubber wood tends to fail at this area. Tropical-mix wood particleboard has strengths comparable to MDF, however at a fraction of the cost, therefore it is still widely used in the market today. Tropical-mix wood has a higher moisture resistance as compared to rubber-wood, however glue type also plays an important role in it. Tropical-mix wood is usually heavier in weight due to its difference in raw material and density (more compact in a sense). Rubber wood has a bright look (yellowish) due to the color of rubber wood, with tropical-mix wood having a brown color finish. Both products are great for lamination purposes and furniture making industries. See also * Engineered wood * Fiberboard * Glued laminated timber * Hardboard * Masonite * Melamine resin the substance used to glue together particleboard * Medium-density fiberboard * Oriented strand board * Plywood * Pressed wood * Waferboard References Category:Composite materials Category:Woodworking materials Category:Engineered wood da:Spånplade de:Holzspanwerkstoff et:Puitlaastplaat es:madera prensada fa:نئوپان it:Truciolato nl:Spaanplaat ja:パーティクルボード pl:Płyta wiórowa ru:Древесно-стружечная плита sk:Drevotrieska sr:Иверица fi:Lastulevy sv:Spånskiva tr:sunta